Field of the Invention
The present invention relates to lighting devices capable of changing the light irradiation range.
Description of the Related Art
Heretofore, there have been known lighting devices capable of changing the light irradiation range (the irradiation range of the lighting devices) (hereinafter also referred to as zoom strobe devices). Some of such zoom strobe devices use a method in which the irradiation range is changed by changing the distance between a light emitting portion including a light source and a reflection umbrella reflecting light emitted from the light source and an optical panel disposed in front of the light emitting portion and refracting light from the light emitting portion. When using this method, for example, the irradiation range is widened by reducing the distance between the optical panel and the light emitting portion when performing wide-angle photographing, in which the angle of view is widened, with a photographing device, and the irradiation range is narrowed by increasing the distance between the optical panel and the light emitting portion when performing telephoto photographing, in which the angle of view is narrowed, with the photographing device.
In such zoom strobe devices, it is necessary to obtain the irradiation range suitable for wide-angle photographing of the photographing device and the quantity of light suitable for telephoto photographing of the photographing device. So, Japanese Patent Laid-Open No. 2008-129301 and Japanese Patent Laid-Open No. 2005-43688 propose a strobe device in which different optical systems are formed in the vicinity of the center of an optical panel used in wide-angle photographing and in the peripheral part of the optical panel used in telephoto photographing.
Japanese Patent Laid-Open No. 2008-129301 discloses a strobe device that has, in the central part of an optical panel, a collecting optical system having the same area as the opening area of a light emitting portion and another collecting optical system in the peripheral part, and in which the collecting optical system in the central part is wide compared to the peripheral part.
Japanese Patent Laid-Open No. 2005-43688 discloses a strobe device having a plurality of optical panels having different surface shapes.
In the strobe device disclosed in Japanese Patent Laid-Open No. 2008-129301, the light distribution in a wide-angle state in which the irradiation range is maximized can be improved. However, the region of the optical panel that is used in the wide-angle state is also used in a telephoto state in which the irradiation range is minimized, and therefore the quantity of light decreases. In order to obtain the necessary quantity of light in the strobe device disclosed in Japanese Patent Laid-Open No. 2008-129301, there is no choice but to increase the travel distance of the light emitting portion. Doing so increases the size of the strobe device.
The strobe device disclosed in Japanese Patent Laid-Open No. 2005-43688 employs a plurality of optical panels and needs a complex configuration. In addition, since the number of components increases, the size and cost of the strobe device increase.